Reactor Cavity Cooling System (RCCS)

The Reactor Cavity Cooling System (RCCS) is a new passive safety
system designed for the next generation of nuclear power plants,
and it will be incorporated into High Temperature Gas-Cooled
Reactors (HTGR), which is one of the proposed Generation IV reactor
designs. This system was conceived to guarantee the integrity of
the fuel, the reactor vessel, and the structures inside the reactor
cavity by removing heat from the cavity during both normal
operation and accident scenarios.

Typical HTGR plant Configuration

Two different RCCS designs are currently under discussion. The
design proposed by General Atomic is a natural convection,
air-based cooling system with no pumps, circulators, valves, or
other active components and is designed to operate continuously in
all modes of plant operation. The second configuration, proposed by
AREVA, is a constant flow, water-based cooling system that operates
at low-temperature and low pressure. Water temperatures are below
30°C during normal active operation, reaching the boiling point
only during emergency passive operation.

The thermal-hydraulic laboratory has worked on both designs,
designing, constructing, and operating a water-cooled RCCS
experimental facility and an air-cooled experimental facility.

The experimental data produced have been compared with
simulations results generated using systems codes (RELAP5-3D) and
CFD codes (STARCCM+).